1. Field of the Invention
The present invention relates to the field of noise suppression, and more particularly to methods, apparatus and systems for retrofitting existing refuse containers and hauling systems to reduce noise during unloading of such containers, as well as constructing new equipment to incorporate the invention.
2. Description of the Related Art
Presently, commercial refuse containers are constructed from steel and come in a variety of form factors, the most prevalent being 3 and 4 cubic yard sizes. Early advancements in the art of refuse handling included the adaptation of such containers to be handled by lifting equipment. In particular, refuse containers were fitted with fork pockets so as to receive adjustable fork assemblies mounted to mobile refuse collection vehicles. By utilizing collection vehicles equipped with lifting forks, and servicing containers fitted with fork pockets, significant gains in speed, safety, and efficiency have been realized. However, an unintended consequence has been the noise resulting from the engagement of the container by the forks as well as the removal of refuse from the container when shaken (as is often times the case) to ensure that all debris has been removed.
A principal reason for the significant noise emanating from the container is the fact that the container is nearly always a hollow steel structure. Operational noises from both the vehicle and the container during refuse removal are amplified by the volume defined by the container. While constructing a container from different material may solve the noise problem, the process would likely have to be phased.
In view of the foregoing, it is desirable to incorporate a noise suppression scheme so that existing steel refuse containers can continue to be used but are modified to reduce the amplification and/or transmission of vibrations that occur during unloading of the container by a fork equipped vehicle.
The invention is directed on the one hand to retrofitting existing containers that are adapted for use with vehicles having lifting forks for elevating and maneuvering such containers, as well as retrofitting the vehicle forks, and on the other hand to constructing new equipment to include the invention. An apparatus according to the invention comprises a liner formed from a vibration absorbing material for insertion into a pocket associated with a container. Alternatively to or in conjunction with the liner, either a glove formed from a vibration absorbing material can be inserted over a lifting fork on a fork bearing, lifting apparatus, or a rail formed from a vibration absorbing material can be fitted to at least a portion of a lifting fork on the fork bearing, lifting apparatus. In all cases, the liner or glove/rail is preferably constructed from a durable material having very low vibration transmission properties and/or high damping properties. The invention is also directed to methods relating to the use and incorporation of the apparatus, and systems incorporating more than one component thereof.
In a preferred embodiment, ultra high molecular weight (UHMW) polyethylene is chosen as the vibration absorbing material. However, it is to be noted that the invention includes metallic, non-metallic, and hybrid materials, with the ultimate selection criteria resulting in a reduction in vibration transmission between the container and the lifting equipment. Thus, a vibration absorbing material impregnated with metallic elements is within the scope of this invention as would be a laminate construction of metallic and non-metallic strips.
The liner and glove embodiments of the invention are preferably formed to frictionally fit, respectively, within an existing container pocket or over an existing lifting fork. While such a fit is sufficient to enable the invention (alternative means to secure the liner and/or glove are contemplated such as by use of adhesives, fasteners, and the like), each apparatus preferably includes means for preventing the separation of one or more apparatus from the supporting structure, to prevent the unintentional dislodgment of a liner or glove.
The liner embodiment of the invention is formed to have outer dimensions that are sufficient to frictionally fit, with or without additional treatment, within the container pocket, and internal dimensions sufficient to receive an intended lifting fork, with or without a glove. Thus a cylinder of material is formed by, for example extrusion or rotational molding, to specifically fit a given container pocket.
A feature of the liner is the presence of a lip that extends laterally beyond the cylinder at an end to prevent the liner from exiting the container pocket if pushed by an entering fork. Another feature of the invention is the presence of a bumper that extends unidirectionally from the cylinder at the lip. The bumper serves to insulate the container structure from any lifting fork supporting structure such as a cross member or similar element.
The glove embodiment of the invention is similarly formed to have specific dimensions based upon the structure to which it will be attached. In particular, the internal dimensions of the cylinder that comprises the glove are sufficient to fit over the targeted section of a lifting fork. If the lifting fork also includes a distal end cap, the glove is preferably heated so that it enlarges sufficiently to pass over the cap and returns to a nominal size after cooling.
In the rail embodiment, the lifting fork is preferably modified so as to receive the rail element yet preferably maintain its original dimensions. Thus, if the working length of the rail is 30xe2x80x3xc3x971xe2x80x3, a similarly sized segment of the load bearing portion of the fork is removed to receive the rail. A similar modification can be made with respect to the opposite or lower side of the lifting fork, depending upon design considerations.
A feature of the rail embodiment is a symmetrical or asymmetrical lateral enlargement of its width beyond the corresponding width of the lifting fork. In this manner, lateral movement of a container being engaged by the equipped lifting fork will be modulated by the vibration dampening rail as opposed to the lateral sides of the lifting fork, which do not have vibration dampening properties. Similarly, increased or decreased rail depths are also considered to be viable modifications.
In all embodiments, the internal and external surface characteristics may be other than smooth. Thus, the internal surface of the glove embodiment or the external surface of the liner embodiment may have a ribbed character to enhance the friction fit between these components and a fork or container pocket, respectively. Similarly, the exterior surface of the glove embodiment and the rail embodiment, or the internal surface of the liner embodiment may be ribbed.